<!DOCTYPE HTML>
<style>
div.outer { font-size: 12px; width: 600px }
div.middle { width: 450px; }
div.inner { width: 300px; }
</style>
<!--
In a 450px container, the minimum font size at 15em per line is 30px.
This means we map 0px-45px into 30px-45px, so 12px gets mapped to 34px.
-->
<div class="outer">
  <div class="middle">
    Text in middle.
    <div class="inner">Text in inner.</div>
  </div>
</div>
